1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight. For children and teens, BMI is age- and gender-specific and is referred to as BMI-for-age.

2. BMI Calculation for Teens

The calculator uses the standard BMI formula:

For 13-year-olds, the BMI value is then compared to CDC growth charts to determine the percentile.

3. Understanding Percentiles

Percentile ranges:

• Below 5th percentile: Underweight
• 5th to 85th percentile: Healthy weight
• 85th to 95th percentile: Overweight
• 95th percentile and above: Obese

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For accuracy, measure height without shoes and weight with minimal clothing.

5. Frequently Asked Questions (FAQ)

Q1: Why use percentiles for teens instead of standard BMI categories?
A: Children's body composition varies by age and gender, so percentiles account for normal growth patterns.

Q2: What if my teen's BMI is above the 85th percentile?
A: Consult a healthcare provider for evaluation. They may assess diet, activity levels, and other health indicators.

Q3: How often should BMI be checked for teens?
A: Annual checks are typically sufficient unless there are specific health concerns.

Q4: Are there limitations to BMI for teens?
A: BMI doesn't distinguish between muscle and fat, so athletic teens may have higher BMI without excess fat.

Q5: Where can I find official growth charts?
A: CDC growth charts are available at: https://www.cdc.gov/growthcharts/